Panoramic photography, the taking of a photograph or photographs covering an elongated field of view, has a long history in photography. Perhaps the most primitive method of panoramic photography is the taking of several adjoining photos with a conventional camera and then mounting the prints together in alignment to achieve a complete panorama. Modern techniques adapt this method by using digital cameras to capture the images, and then using computer image processing techniques to align the images and stitch the images together as a single panoramic image.
The continuous development of digital camera technologies along with constantly increasing speed and processing power of computers have laid the foundation for digital imaging systems that are capable of acquiring image data for the automatic creation of wide to entire 360° panoramas, including both still panoramic images and dynamic panoramic movies.
Currently, main-stream panoramic imaging solutions can be generally categorized into the multi-lens approach and the single-lens approach. Multi-lens panoramic camera systems utilize a set of cameras for simultaneous image or video capturing. The cameras are typically arranged in either a parallel fashion or a converged fashion, such that each camera's field of view overlaps with that of at least one other camera. This way, the total field of view covered by the multi-camera systems is significantly enlarged as compared to a conventional single-lens camera. Hence, during panoramic video capturing, a multi-camera panoramic system generates multiple channels of simultaneous video signals, which are immediately output from the multiple cameras and transmitted to a processor, such as an accelerated processing unit (APU) of the multi-camera panoramic system for post-processing.
When using a multi-camera panoramic imaging system to capture multiple video signals, what can happen is that lighting conditions for the different cameras are not uniform, which can result in differences in luminance for the different channels of the video signals. This situation can subsequently lead to non-uniformities in luminance within a panoramic image generated by stitching together the multiple channels of camera images having different luminance levels. Conventional techniques address the problem of non-uniformities in luminance associated with the stitched panoramic images by post-processing the stitched images after the multi-channel of cameras images have been stitched together.